Pneumatic tire having a component containing high trans styrene-isoprene-butadiene rubber

ABSTRACT

The invention is directed to a pneumatic tire having at least one component comprising a vulcanizable rubber composition, wherein the vulcanizable rubber composition comprises, based on 100 parts by weight of elastomer (phr), from about 30 to 100 phr of high trans random SIBR, and from about zero to about 70 phr of at least one additional elastomer, wherein the high trans random SIBR comprises from about 3 to about 30 percent by weight of styrene.

BACKGROUND OF THE INVENTION

It is highly desirable for tires to have good wet skid resistance, lowrolling resistance and good wear characteristics. It has traditionallybeen very difficult to improve a tire's wear characteristics withoutsacrificing its wet skid resistance and traction characteristics. Theseproperties depend, to a great extent, on the dynamic viscoelasticproperties of the rubbers utilized in making the tire.

In order to reduce the rolling resistance and to improve the treadwearcharacteristics of tires, rubbers having a high rebound havetraditionally been utilized in making tire tread rubber compounds. Onthe other hand, in order to increase the wet skid resistance of a tire,rubbers which undergo a large energy loss have generally been utilizedin the tire's tread. In order to balance these two viscoelasticallyinconsistent properties, mixtures of various types of synthetic andnatural rubber are normally utilized in tire treads. For instance,various mixtures of styrene-butadiene rubber and polybutadiene rubberare commonly used as a rubbery material for automobile tire treads.

U.S. Pat. No. 6,103,842 and U.S. application Ser. No. 10/124,006disclose processes and catalyst systems for the copolymerization of1,3-butadiene monomer and styrene monomer into a styrene-butadiene orstyrene-isoprene-butadiene copolymer having a hightrans-1,4-polybutadiene content and having a random distribution ofrepeat units which are derived from styrene. It is also thereindisclosed that styrene-isoprene-butadiene rubber made utilizing thecatalyst system and techniques therein may be used in the preparation oftire tread rubber compounds which exhibit improved wear characteristics.What is not disclosed is that superior wear characteristics may beobtained using a low styrene content in the high trans random SIBR.

SUMMARY OF THE INVENTION

The current invention is directed to a pneumatic tire having at leastone component comprising a high trans solutionstyrene-isoprene-butadiene rubber (HTSEBR) with a random distribution ofrepeat units which are derived from styrene. The invention is based onthe highly surprising and unexpected discovery that a desirable balanceof properties may be realized by using a HTSIBR with a low styrenecontent.

It is then an object of the present invention to provide a pneumatictire having at least one component comprising a vulcanizable rubbercomposition, wherein the vulcanizable rubber composition comprises,based on 100 parts by weight of elastomer (phr), from about 30 to 100phr of high trans random SIBR, and from about zero to about 70 phr of atleast one additional elastomer, wherein the high trans random SIBRcomprises from about 3 to about 30 percent by weight of styrene.

DESCRIPTION OF THE INVENTION

The pneumatic tire of the present invention has at least one componentcomprising a high trans solution styrene-isoprene-butadiene rubberHTSIBR. By HTSIBR, it is meant an SIBR produced by a solution method andhaving a percentage of trans-1,4-butadiene conformation in thepolybutadiene segments of the polymer of greater than 60 percent byweight. Alternatively, suitable HTSIBR may have a percentage oftrans-1,4-butadiene conformation in the polybutadiene segments of thepolymer of greater than 70 percent by weight. Suitable HTSIBR maycontain from about 3 to about 30 percent by weight of styrene.Alternatively, suitable HTSIBR may contain from about 3 to about 20percent by weight of styrene. Alternatively, suitable HTSIBR may containfrom about 3 to about 10 percent by weight of styrene.

Suitable HTSIBR may be made by any of the suitable solutionpolymerization methods as are known in the art. In one embodiment,suitable HTSIBR may be made using the methods of U.S. Pat. No.6,103,842. In another embodiment, suitable HTSIBR may be made using themethods of U.S. application Ser. No. 10/124,006.Styrene-isoprene-butadiene rubbers so made may contain from about 2weight percent to about 50 weight percent styrene, from about 2 to about20 percent by weight of isoprene, and from about 50 weight percent toabout 98 weight percent 1,3-butadiene. However, in some cases, theamount of styrene included will be as low as about 1 weight percent. Inone embodiment of the present invention, suitablestyrene-isoprene-butadiene rubber so made will contain from about 3weight percent to about 30 weight percent styrene, from about 2 to about20 percent by weight of isoprene, and from about 70 weight percent toabout 97 weight percent 1,3-butadiene. In another embodiment, suitablestyrene-isoprene-butadiene rubber will contain from about 3 weightpercent to about 20 weight percent styrene, from about 2 to about 20percent by weight of isoprene, and from about 80 weight percent to about97 weight percent 1,3-butadiene. In another embodiment, suitablestyrene-isoprene-butadiene rubber will contain from about 3 weightpercent to about 10 weight percent styrene, from about 2 to about 20percent by weight of isoprene, and from about 90 weight percent to about97 weight percent 1,3-butadiene. These styrene-isoprene-butadienerubbers typically have a melting point which is within the range ofabout below 44° C. Higher styrene content HTSIBR may exhibit no meltingpoint.

The styrene-isoprene-butadiene rubber will typically have a glasstransition temperature in a range of from about −90° C. to about −70°C.; alternatively from about −85° C. to about −75° C.

In suitable styrene-isoprene-butadiene rubbers containing less thanabout 30 weight percent bound styrene, the distribution of repeat unitsderived from styrene, isoprene and butadiene is essentially random. Theterm “random”, as used herein, means that less than 10 percent of thetotal quantity of repeat units derived from styrene are in blockscontaining more than five styrene repeat units. In other words, morethan 90 percent of the repeat units derived from styrene are in blockscontaining five or fewer repeat units. About 20% of the repeat unitsderived from styrene will be in blocks containing only one styrenerepeat unit. Such blocks containing one styrene repeat unit are bound onboth sides by repeat units which are derived from 1,3-butadiene.

In suitable styrene-isoprene-butadiene rubbers containing less thanabout 20 weight percent bound styrene, less than 4 percent of the totalquantity of repeat units derived from styrene are in blocks containingfive or more styrene repeat units. In other words, more than 96 percentof the repeat units derived from styrene are in blocks containing lessthan five repeat units. In such styrene-isoprene-butadiene rubbers, over25 percent of repeat units derived from styrene will be in blockscontaining only one styrene repeat unit, over 60 percent of the repeatunits derived from styrene will be in blocks containing less than 3repeat units and over 90 percent of the repeat units derived fromstyrene will be in blocks containing 4 or fewer repeat units.

In suitable styrene-isoprene-butadiene rubbers containing less thanabout 10 weight percent bound styrene, less than 1 percent of the totalquantity of repeat units derived from styrene are in blocks containing 5or more styrene repeat units. In other words, more than 99 percent ofthe repeat units derived from styrene are in blocks containing 4 or lessrepeat units. In such styrene-isoprene-butadiene rubbers, at least about50 percent of repeat units derived from styrene will be in blockscontaining only one styrene repeat unit and over about 85 percent of therepeat units derived from styrene will be in blocks containing less than3 repeat units.

Suitable styrene-isoprene-butadiene copolymers also have a consistentcomposition throughout their polymer chains. In other words, the styrenecontent of the polymer will be the same from the beginning to the end ofthe polymer chain. No segments of at least 100 repeat units within thepolymer will have a styrene content which differs from the total styrenecontent of the polymer by more than 10 percent. Suchstyrene-isoprene-butadiene copolymers will typically contain no segmentshaving a length of at least 100 repeat units which have a styrenecontent which differs from the total styrene content of the polymer bymore than about 5 percent.

In the broadest embodiment, suitable HTSIBR may be made by any of thesuitable solution polymerization methods as are known in the art. In oneembodiment, suitable HTSIBR may be produced using a process as taught inU.S. application Ser. No. 10/124,006, fully incorporated herein byreference, that comprises copolymerizing styrene, isoprene, and1,3-butadiene in an organic solvent in the presence of a catalyst systemthat is comprised of

(A) an organolithium compound,

(B) a group IIa metal salt selected from the group consisting of groupIIa metal salts of amino glycols and group IIa metal salts of glycolethers, and

(C) an organometallic compound selected from the group consisting oforganoaluminum compounds and organomagnesium compounds.

In another embodiment, suitable HTSIBR may be produced using a processas taught in U.S. Pat. No. 6,103,842, fully incorporated herein byreference, that comprises copolymerizing styrene, isoprene, and1,3-butadiene under isothermal conditions in an organic solvent in thepresence of a catalyst system which consists essentially of

(A) an organolithium compound,

(B) a barium alkoxide and

(C) a lithium alkoxide.

In one embodiment, the pneumatic tire of the present invention mayinclude a component comprising between about 30 and about 100 parts byweight of HTSEBR. The component may also include between zero and up to70 parts by weight of other elastomers as are known in the art, to makeup a total 100 parts by weight of elastomer. In another embodiment, thepneumatic tire of the present invention may include a componentcomprising between about 50 and about 100 parts by weight of HTSIBR. Thecomponent may also include between zero and up to 50 parts by weight ofother elastomers as are known in the art, to make up a total 100 partsby weight of elastomer.

Other elastomers that may be used along with the HTSIBR may includevarious general purpose elastomers as are known in the art. The phrase“rubber or elastomer containing olefinic unsaturation” is intended toinclude both natural rubber and its various raw and reclaim forms aswell as various synthetic rubbers. In the description of this invention,the terms “rubber” and “elastomer” may be used interchangeably, unlessotherwise prescribed. The terms “rubber composition”, “compoundedrubber” and “rubber compound” are used interchangeably to refer torubber which has been blended or mixed with various ingredients andmaterials, and such terms are well known to those having skill in therubber mixing or rubber compounding art. Representative syntheticpolymers are the homopolymerization products of butadiene and itshomologues and derivatives, for example, methylbutadiene,dimethylbutadiene and pentadiene as well as copolymers such as thoseformed from butadiene or its homologues or derivatives with otherunsaturated monomers. Among the latter are acetylenes, for example,vinyl acetylene; olefins, for example, isobutylene, which copolymerizeswith isoprene to form butyl rubber; vinyl compounds, for example,acrylic acid, acrylonitrile (which polymerize with butadiene to formNBR), methacrylic acid and styrene, the latter compound polymerizingwith butadiene to form SBR, as well as vinyl esters and variousunsaturated aldehydes, ketones and ethers, e.g., acrolein, methylisopropenyl ketone and vinylethyl ether. Specific examples of syntheticrubbers include neoprene (polychloroprene), polybutadiene (includingcis-1,4-polybutadiene), polyisoprene (including cis-1,4-polyisoprene),butyl rubber, halobutyl rubber such as chlorobutyl rubber or bromobutylrubber, styrene/isoprene/butadiene rubber, copolymers of 1,3-butadieneor isoprene with monomers such as styrene, acrylonitrile and methylmethacrylate, as well as ethylene/propylene terpolymers, also known asethylene/propylene/diene monomer (EPDM), and in particular,ethylene/propylene/dicyclopentadiene terpolymers. Additional examples ofrubbers which may be used include a carboxylated rubber, silicon-coupledand tin-coupled star-branched polymers. The preferred rubber orelastomers are polybutadiene, SBR, and natural rubber.

In one aspect, the rubber to be combined with the HTSIBR is preferablyone or more diene-based rubbers. For example, one or more rubbers ispreferred such as cis 1,4-polyisoprene rubber (natural or synthetic,although natural is preferred), 3,4-polyisoprene rubber,styrene/isoprene/butadiene rubber, emulsion and solution polymerizationderived styrene/butadiene rubbers, cis 1,4-polybutadiene rubbers andemulsion polymerization prepared butadiene/acrylonitrile copolymers.

The commonly-employed siliceouspigments which may be used in the rubbercompound include conventional pyrogenic and precipitated siliceouspigments (silica), although precipitated silicas are preferred. Theconventional siliceous pigments preferably employed in this inventionare precipitated silicas such as, for example, those obtained by theacidification of a soluble silicate, e.g., sodium silicate.

Such conventional silicas might be characterized, for example, by havinga BET surface area, as measured using nitrogen gas, preferably in therange of about 40 to about 600, and more usually in a range of about 50to about 300 square meters per gram. The BET method of measuring surfacearea is described in the Journal of the American Chemical Society,Volume 60, Page 304 (1930).

The conventional silica may also be typically characterized by having adibutylphthalate (DBP) absorption value in a range of about 100 to about400, and more usually about 150 to about 300.

The conventional silica might be expected to have an average ultimateparticle size, for example, in the range of 0.01 to 0.05 micron asdetermined by the electron microscope, although the silica particles maybe even smaller, or possibly larger, in size.

Various commercially available silicas may be used, such as, only forexample herein, and without limitation, silicas commercially availablefrom PPG Industries under the Hi-Sil trademark with designations 210,243, etc; silicas available from Rhodia, with, for example, designationsof Z1165MP and Z165GR and silicas available from Degussa AG with, forexample, designations VN2 and VN3, etc.

Commonly-employed carbon blacks can be used as a conventional filler.Representative examples of such carbon blacks include N110, N121, N220,N231, N234, N242, N293, N299, S315, N326, N330, M332, N339, N343, N347,N351, N358, N375, N539, N550, N582, N630, N642, N650, N683, N754, N762,N765, N774, N787, N907, N908, N990 and N991. These carbon blacks haveiodine absorptions ranging from 9 to 145 g/kg and DBP number rangingfrom 34 to 150 cm³/100 g.

It may be preferred to have the rubber composition for use in the tirecomponent to additionally contain a conventional sulfur-containingorganosilicon compound. Examples of suitable sulfur-containingorganosilicon compounds are of the formula:

Z—Alk—S _(n) —Alk—Z

in which Z is selected from the group consisting of

where R⁶ is an alkyl group of 1 to 4 carbon atoms, cyclohexyl or phenyl;R⁷ is alkoxy of 1 to 8 carbon atoms, or cycloalkoxy of 5 to 8 carbonatoms; Alk is a divalent hydrocarbon of 1 to 18 carbon atoms and n is aninteger of 2 to 8.

Specific examples of sulfur-containing organosilicon compounds which maybe used in accordance with the present invention include:3,3′-bis(trimethoxysilylpropyl)disulfide,3,3′-bis(triethoxysilyipropyl)disulfide,3,3′-bis(triethoxysilylpropyl)tetrasulfide,3,3′-bis(triethoxysilylpropyl)octasulfide,3,3′-bis(trimethoxysilylpropyl)tetrasulfide,2,2′-bis(triethoxysilylethyl)tetrasulfide,3,3′-bis(trimethoxysilylpropyl)trisulfide,3,3′-bis(triethoxysilylpropyl)trisulfide,3,3′-bis(tributoxysilylpropyl)disulfide,3,3′-bis(trimethoxysilylpropyl)hexasulfide,3,3′-bis(trimethoxysilylpropyl)octasulfide,3,3′-bis(trioctoxysilylpropyl)tetrasulfide,3,3′-bis(trihexoxysilylpropyl)disulfide,3,3′-bis(tri-2″-ethylhexoxysilylpropyl)trisulfide,3,3′-bis(triisooctoxysilylpropyl)tetrasulfide,3,3′-bis(tri-t-butoxysilylpropyl)disulfide, 2,2′-bis(methoxy diethoxysilyl ethyl)tetrasulfide, 2,2′-bis(tripropoxysilylethyl)pentasulfide,3,3′-bis(tricyclonexoxysilylpropyl)tetrasulfide,3,3′-bis(tricyclopentoxysi lylpropyl)trisulfide,2,2′-bis(tri-2″-methylcyclohexoxysilylethyl)tetrasulfide,bis(trimethoxysilylmethyl)tetrasulfide, 3-methoxy ethoxy propoxysilyl3′-diethoxybutoxy-silylpropyltetrasulfide, 2,2′-bis(dimethylmethoxysilylethyl)disulfide, 2,2′-bis(dimethyl sec.butoxysilylethyl)trisulfide, 3,3′-bis(methylbutylethoxysilyipropyl)tetrasulfide, 3,3′-bis(dit-butylmethoxysilylpropyl)tetrasulfide, 2,2′-bis(phenyl methylmethoxysilylethyl)trisulfide, 3,3′-bis(diphenylisopropoxysilyipropyl)tetrasulfide, 3,3′-bis(diphenylcyclohexoxysilyipropyl)disulfide, 3,3′-bis(dimethylethylmercaptosilyipropyl)tetrasulfide, 2,2′-bis(methyldimethoxysilylethyl)trisulfide, 2,2′-bis(methylethoxypropoxysilylethyl)tetrasulfide, 3,3′-bis(diethylmethoxysilyipropyl)tetrasulfide, 3,3′-bis(ethyl di-sec.butoxysilyipropyl)disulfide, 3,3′-bis(propyldiethoxysilylpropyl)disulfide, 3,3′-bis(butyldimethoxysilyipropyl)trisulfide, 3,3′-bis(phenyldimethoxysilylpropyl)tetrasulfide, 3-phenyl ethoxybutoxysilyl3′-trimethoxysilylpropyl tetrasulfide,4,4′-bis(trimethoxysilylbutyl)tetrasulfide,6,6′-bis(triethoxysilylhexyl)tetrasulfide, 12,12′-bis(triisopropoxysilyldodecyl)disulfide, 18,18′-bis(trimethoxysilyloctadecyl)tetrasulfide,18,18′-bis(tripropoxysilyloctadecenyl)tetrasulfide,4,4′-bis(trimethoxysilyl-buten-2-yl)tetrasulfide, 4,4′-bis(trimethoxysilylcyclohexylene)tetrasulfide,5,5′-bis(dimethoxymethylsilylpentyl)trisulfide,3,3′-bis(trimethoxysilyl-2-methylpropyl)tetrasulfide,3,3′-bis(dimethoxyphenylsilyl-2-methylpropyl)disulfide.

The preferred sulfur containing organosilicon compounds are the3,3′-bis(trimethuxy or triethoxy silyipropyl)sulfides. The mostpreferred compounds are 3,3′-bis(triethoxysilylpropyl)disulfide and3,3′-bis(triethoxysilylpropyl)tetrasulfide. Therefore, as to formula I,preferably Z is

where R⁷ is an alkoxy of 2 to 4 carbon atoms, with 2 carbon atoms beingparticularly preferred; alk is a divalent hydrocarbon of 2 to 4 carbonatoms with 3 carbon atoms being particularly preferred; and n is aninteger of from 2 to 5 with 2 and 4 being particularly preferred.

The amount of the sulfur-containing organosilicon compound of formula Iin a rubber composition will vary depending on the level of otheradditives that are used. Generally speaking, the amount of the compoundof formula I will range from 0.5 to 20 phr. Preferably, the amount willrange from 1 to 10 phr.

It is readily understood by those having skill in the art that therubber composition would be compounded by methods generally known in therubber compounding art, such as mixing the various sulfur-vulcanizableconstituent rubbers with various commonly-used additive materials suchas, for example, sulfur donors, curing aids, such as activators andretarders and processing additives, such as oils, resins includingtackifying resins and plasticizers, fillers, pigments, fatty acid, zincoxide, waxes, antioxidants and antiozonants and peptizing agents. Asknown to those skilled in the art, depending on the intended use of thesulfur vulcanizable and sulfur-vulcanized material (rubbers), theadditives mentioned above are selected and commonly used in conventionalamounts. Representative examples of sulfur donors include elementalsulfur (free sulfur), an amine disulfide, polymeric polysulfide andsulfur olefin adducts. Preferably, the sulfur-vulcanizing agent iselemental sulfur. The sulfur-vulcanizing agent may be used in an amountranging from 0.5 to 8 phr, with a range of from 1.5 to 6 phr beingpreferred. Typical amounts of tackifier resins, if used, comprise about0.5 to about 10 phr, usually about 1 to about 5 phr. Typical amounts ofprocessing aids comprise about 1 to about 50 phr. Such processing aidscan include, for example, aromatic, naphthenic, and/or paraffinicprocessing oils. Typical amounts of antioxidants comprise about 1 toabout 5 phr. Representative antioxidants may be, for example,diphenyl-p-phenylenediamine and others, such as, for example, thosedisclosed in the Vanderbilt Rubber Handbook (1978), Pages 344 through346. Typical amounts of anticzonants comprise about 1 to 5 phr. Typicalamounts of fatty acids, if used, which can include stearic acid compriseabout 0.5 to about 3 phr. Typical amounts of zinc oxide comprise about 2to about 5 phr. Typical amounts of waxes comprise about 1 to about 5phr. Often microcrystalline waxes are used. Typical amounts of peptizerscomprise about 0.1 to about 1 phr. Typical peptizers may be, forexample, pentachlorothiophenol and dibenzamidodiphenyl disulfide.

Accelerators are used to control the time and/or temperature requiredfor vulcanization and to improve the properties of the vulcanizate. Inone embodiment, a single accelerator system may be used, i.e., primaryaccelerator, The primary accelerator(s) may be used in total amountsranging from about 0.5 to about 4, preferably about 0.8 to about 1.5,phr. In another embodiment, combinations of a primary and a secondaryaccelerator might be used with the secondary accelerator being used insmaller amounts, such as from about 0.05 to about 3 phr, in order toactivate and to improve the properties of the vulcanizate. Combinationsof these accelerators might be expected to produce a synergistic effecton the final properties and are somewhat better than those produced byuse of either accelerator alone. In addition, delayed actionaccelerators may be used which are not affected by normal processingtemperatures but produce a satisfactory cure at ordinary vulcanizationtemperatures. Vulcanization retarders might also be used. Suitable typesof accelerators that may be used in the present invention are amines,disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides,dithiocarbamates and xanthates. Preferably, the primary accelerator is asulfenamide. If a second accelerator is used, the secondary acceleratoris preferably a guanidine, dithiocarbamate or thiuram compound.

The mixing of the rubber composition can be accomplished by methodsknown to those having skill in the rubber mixing art. For example theingredients are typically mixed in at least two stages, namely at leastone non-productive stage followed by a productive mix stage. The finalcuratives including sulfur-vulcanizing agents are typically mixed in thefinal stage which is conventionally called the “productive” mix stage inwhich the mixing typically occurs at a temperature, or ultimatetemperature, lower than the mix temperature(s) than the precedingnon-productive mix stage(s). The terms “non-productive” and “productive”mix stages are well known to those having skill in the rubber mixingart. The rubber composition may be subjected to a thermomechanicalmixing step. The thermomechanical mixing step generally comprises amechanical working in a mixer or extruder for a period of time suitablein order to produce a rubber temperature between 140° C. and 190° C. Theappropriate duration of the thermomechanical working varies as afunction of the operating conditions and the volume and nature of thecomponents. For example, the thermomechanical working may be from 1 to20 minutes.

The rubber composition may be incorporated in a variety of rubbercomponents of the tire. For example, the rubber component may be a tread(including tread cap and tread base), sidewall, apex, chafer, sidewallinsert, wirecoat or innerliner. Preferably, the compound is a tread.

The pneumatic tire of the present invention may be a race tire,passenger tire, aircraft tire, agricultural, earthmover, off-the-road,truck tire and the like. Preferably, the tire is a passenger or trucktire. The tire may also be a radial or bias, with a radial beingpreferred.

Vulcanization of the pneumatic tire of the present invention isgenerally carried out at conventional temperatures ranging from about100° C. to 200° C. Preferably, the vulcanization is conducted attemperatures ranging from about 110° C. to 180° C. Any of the usualvulcanization processes may be used such as heating in a press or mold,heating with superheated steam or hot air. Such tires can be built,shaped, molded and cured by various methods which are known and will bereadily apparent to those having skill in such art.

The following examples are presented for the purposes of illustratingand not limiting the present invention. All parts are parts by weightunless specifically identified otherwise.

EXAMPLE I

In this t ample, two high trans random solution SIBR (HTSIBR) polymersprepared following the teachings of U.S. application Ser. No. 10/124,006were compounded and tested for various physical properties. Thesepolymers are characterized as indicated in Table 1.

The polymers were compounded with SBR and standard amounts ofconventional curatives and processing aids as indicated in Table 2, andcured with a standard cure cycle. Cured samples were evaluated forvarious physical properties following standard tests protocols asindicated in Table 3.

TABLE 1 Sample S/I/BR⁽¹⁾ ML1 + 4 (100° C.) T_(g)(C) T_(m)(C) 1 10/10/8087 −85 24 2 5/5/90 106 −82 18 ⁽¹⁾styrene/isoprene/butadiene weight ratio

TABLE 2 Sample A Component (Control) Sample B Sample C IBR⁽²⁾ 30 — —BR⁽³⁾ 12 — — NR⁽⁴⁾ 20 — — SIBR 1 — 62 — SIBR 2 — — 62 SBR (oil extended)52.25 52.25 52.25 (38 phr RHC) Z165GR Silica 50 50 50 Coupling Agent4.94 4.94 4.94 Stearic Acid 2 2 2 ZnO 3.5 3*5 3.5 Wax 2.25 2.25 2.25Antidegradants 3 3 3 Curatives 2.6 2.6 2.6 Sulfur 1.8 1.8 1.8⁽²⁾isoprene-butadiene rubber ⁽³⁾polybutadiene ⁽⁴⁾natural rubber

TABLE 3 Sample A B C Modulus, 100% (MPa) 1.36 1.43 1.46 Modulus, 300%(MPa) 5.41 5.64 5.69 Tensile (MPa) 17.41 18.63 20.67 Elongation @ Break,% 625 611 626 Energy, J 148 154 170 Hardness, RT 60.3 63.7 65.4Hardness, 100 C 54.8 57.6 58.6 Rebound, RT 51.8 50.2 48.4 Rebound, 100 C67.2 65.1 63.3 DIN Abrasion (cc) 102 88 83 Relative volume loss StreblerAdhesion to Self 105 110 140 (S.S. avg. peak load, N)

Samples B and C show improved energy to break, higher hardness, highertensile strength and tear strength and improved abrasion resistancecompared to Sample A (Control).

The samples demonstrate the unexpectedly superior tear, rebound, andabrasion properties obtained for the HTSEBR samples. This isparticularly surprising, since generally improvements in tear strengthare realized only with a compromise in rebound and abrasion, and viceversa. Further, the tear values for the lower styrene content aresurprisingly high. For example, the tear (peel or Strebler adhesion)strength values for Samples B and C having styrene contents in a rangeof about 5 to about 10 percent are significantly higher than the tearvalues for Samples A. DIN abrasion for samples B and C is alsosignificantly greater than for the control.

While certain representative embodiments and details have been shown forthe purpose of illustrating the subject invention, it will be apparentto those skilled in this art that various changes and modifications canbe made therein without departing from the scope of the subjectinvention.

What is claimed is:
 1. A pneumatic tire having a component comprising avulcanizable rubber composition comprising, based on 100 parts by weightof elastomer (phr), (A) from about 30 to 100 phr of high trans randomSIBR comprising from about 3 to about 30 percent by weight of styrene,said high trans random SIBR being produced by a process that comprisescopolymerizing styrene, isoprene and 1,3-butadiene in an organic solventin the presence of a catalyst system that is comprised of (1) anorganolithium compound, (2) a group IIa metal salt selected from thegroup consisting of group IIa metal salts of amino glycols, and groupIIa metal salts of glycol ethers, and (3) an organometallic compoundselected from the group consisting of organoaluminum compounds andorganomagnesium compounds; and (B) from about zero to about 70 phr of atleast one additional elastomer.
 2. The pneumatic tire of claim 1,wherein said vulcanizable rubber composition comprises from about 50 toabout 100 phr of high trans random SIBR comprising from about 3 to about30 percent by weight of styrene, and from about 10 to about 50 phr of atleast one additional elastomer.
 3. The pneumatic tire of claim 1,wherein said high trans random SIBR comprises from about 3 to about 20percent by weight of styrene.
 4. The pneumatic tire of claim 1, whereinsaid high trans random SIBR comprises from about 3 to about 10 percentby weight of styrene.
 5. The pneumatic tire of claim 1, wherein saidhigh trans random SIBR has a trans content of greater than 60 percent byweight.
 6. The pneumatic tire of claim 1, wherein said high trans randomSIBR has a trans content of greater than 70 percent by weight.
 7. Thepneumatic tire of claim 1, wherein said high trans random SIBR has aglass transition temperature in a range of from about −90° C. to about−70° C.
 8. The pneumatic tire of claim 1, wherein said component isselected from the group consisting of tread cap, tread base, sidewall,apex, chafer, sidewall insert, wirecoat and innerliner.
 9. The pneumatictire of claim 1, wherein said component is a tread cap or tread base.10. The pneumatic tire of claim 1, wherein said at least one additionalelastomer is selected from the group consisting of cis 1,4-polyisoprenerubber (natural or synthetic, although natural is preferred),3,4-polyisoprene rubber, styrene/isoprene/butadiene rubber,styrene/isoprene rubber, emulsion and solution polymerization derivedstyrene/butadiene rubbers, cis 1,4-polybutadiene rubbers and emulsionpolymerization prepared butadiene/acrylonitrile copolymers.
 11. Thepneumatic tire of claim 1, wherein said at least one additionalelastomer is styrene-butadiene rubber.
 12. The pneumatic tire of claim1, wherein said vulcanizable rubber composition further comprises fromabout 20 to about 100 phr of carbon black.
 13. The pneumatic tire ofclaim 1, wherein said vulcanizable rubber composition further comprisesfrom about 20 to about 100 phr of silica.
 14. The pneumatic tire ofclaim 1, wherein less than 10 percent of the total quantity of repeatunits derived from styrene in said high trans random SIBR are in blockscontaining more than five styrene repeat units.
 15. The pneumatic tireof claim 1, wherein less than 4 percent of the total quantity of repeatunits derived from styrene in said high trans random SIBR are in blockscontaining 5 or more styrene repeat units.
 16. The pneumatic tire ofclaim 1, wherein less than 1 percent of the total quantity of repeatunits derived from styrene in said high trans random SIBR are in blockscontaining 5 or more styrene repeat units.